1. Field of the Invention
The present invention relates generally to the field of structural connectors, and more particularly, to a holddown connector for connecting a vertical wood framing stud or the like to a generally horizontal foundation member usually formed of concrete, wood, or some combination thereof.
2. Description of the Prior Art
In the construction industry, vertical wooden stud elements are commonly connected to a wooden sill by toenailing or the like. The sill is in turn secured to a concrete foundation by threaded bolts anchored into the foundation or other similar connecting means. Although toenailing is generally a strong enough connection for withstanding most stresses placed on the building, it is inadequate to anchor the building to the foundation where the buildings are subject to significant seismic and wind loads such as those generated by earthquakes, hurricanes, typhoons and the like. For buildings which are subject to such forces, holddown connectors have been utilized to more securely connect the vertical studs, and thus the building structure, to the foundation.
In general, a holddown connector is a metallic connector having a generally vertical back plate with one or more openings for connection to a vertical stud, a pair of side plates integrally formed with the back plate and extending forwardly and downwardly from the edges thereof and a generally horizontally disposed base plate or seat extending between bottom edges of the side plates. The base plate includes an opening for connection to the generally horizontally disposed foundation or sill.
Several holddown connectors currently exist in the art. One such hold down is constructed of heavy gauge metal in which the back plate, side plates and base plate are individually fabricated, welded together and then painted. As a result, such connectors tend to be quite costly.
A second prior art holddown connector is illustrated in U.S. Pat. No. 4,665,672 issued to Commins et al. on May 19, 1987. This holddown connector is constructed from a single piece of sheet metal and includes a seat member formed with a bolt opening, a pair of side members integrally joined with the seat and a pair of overlapping back members formed with one or more overlapping and aligned openings for a connection to a vertical building stud.
A still further prior art holddown connector is illustrated in U.S. Pat. No. 4,825,621 issued to Jensen on May 2, 1989. This holddown is a one piece structure constructed of sheet metal stock and comprises a single back plate, a pair of side plates and a pair of overlapping first and second base plates with an aligned bolt opening extending therethrough.
Although each of the above identified prior art holddown structures provide adequate connection strength for connecting a vertical building member such as a wooden stud to a generally horizontal member such as a concrete foundation, certain limitations continue to exist with respect to such connectors. With respect to the first connector described above, the cost of fabrication is quite high because they are constructed of individual sections which are welded together to form a rigid structure and then painted.
Although the second and third holddown connectors described above overcome this limitation since they are fabricated from a single piece of sheet metal which is bent into the desired configuration, both of these structures embody either an overlapped back plate or an overlapped base or seat plate with aligned openings therein. Because the holes are normally drilled prior to bending and fabrication, the possibility exists for the aligned openings to be slightly misaligned thereby resulting in difficulty inserting a bolt or other threaded member therethrough. Secondly, because of the overlapped portions, such portions resist stresses individually until they engage the connecting bolt. Thus, there is some limited relative movement and deflection which can occur between the overlapped portions before the retaining feature of the bolt is actually utilized.
Accordingly, there is a continuing need in the art for an improved holddown connector which is essentially constructed of a single piece of material, but which also effectively eliminates the limitations of overlapped back or seat plates of prior connectors.